NASA STS-135 Report #09 6 p.m. CDT Tuesday, July 12, 2011

HOUSTON - Two International Space Station astronauts completed a six-hour, 31-minute spacewalk at 2:53 p.m. CDT Tuesday, retrieving a failed pump module for return to Earth, installing two experiments and repairing a new base for the station's robotic arm.

Flight Engineers Mike Fossum and Ron Garan used that arm, Canadarm2, in their first and most lengthy task, retrieval of the failed 1,400-pound pump module from the station's cooling system that failed last year. Garan rode the arm to the pump module's stowage rack where he and Fossum removed it.

Still on the arm, operated by Atlantis Pilot Doug Hurley and Mission Specialist Sandra Magnus in the station's cupola, Garan took the pump module to a carrier in Atlantis' cargo bay. There Fossum bolted it into place for the ride home.

Coached by intravehicular officer and Atlantis Mission Specialist Rex Walheim, with help from spacewalk capcom and astronaut Steve Bowen in the station flight control room, the spacewalkers moved on to their next task, installation of the Robotic Refueling Mission experiment. The experiment is designed to help in development of ways to robotically refuel satellites in space.

Fossum was making his seventh spacewalk and Garan his fourth (all with Fossum). They removed the refueling experiment from the cargo bay. Fossum, now on the arm, carried the experiment to a platform on Dextre, the Special Purpose Dexterous Manipulator.

Fossum removed the foot restraint he and Garan had used at the end of the Canadarm2, then moved to the front of the Zarya module. There he freed a wire stuck in one latch door at a data grapple fixture installed during the STS-134 mission in May. The fixture can serve as a base for Canadaram2, considerably extending its range of operation.

Meanwhile, Garan deployed a materials experiment also installed during STS-134, on a carrier on the station's starboard truss. The eighth in a series of station materials experiments, it focuses on optical reflector materials. It was not deployed during the previous flight because of concerns about outgasing from insulation on the nearby Alpha Magnetic Spectrometer experiment, also installed during the earlier mission.

Back together again, the two spacewalkers moved on to Pressurized Mating Adaptor 3 on the Tranquility node. They installed an insulating cover on the end of the PMA, an area exposed to considerable sunshine.

Inside the shuttle-station complex, transfer of material from the Raffaello multipurpose logistics module began. The work to unload the more than 9,400 pounds of supplies and equipment brought up by Raffaello and then repack it with 5,700 pounds of equipment, supplies and trash to return home will continue for much of Atlantis stay at the station.

The next status report will be issued after crew wakeup or earlier if warranted. The crew is scheduled to awaken just before 1:30 a.m. Wednesday.